There's no reason to delete an account, there's a loophole that can be used for criminal to take advantage over it. Similar like Bitcoin address can't be deleted, there's no point to delete it.
Note that there are known and unknown services that scrape data from the forum, so consider that anything you post after clicking on post button is recorded and cannot be deleted.
He can contact the scrapers to delete the post because I remember they did remove someone who post their private key.